“Rock fluorescence,” she said, and suddenly he understood.
“Oh, of course!” With the sun just below the horizon, no direct sunlight illuminated the surface…but the sky scattered sunlight. Rayleigh scattering, he thought: On Earth the scattered sky-light was blue, but with no ozone layer, on Mars the ultraviolet was even stronger, and the sky must be emitting a softly invisible bath of black light. In the near darkness the faint fluorescence of the rocks under the invisible sky-glow was just barely bright enough to see. “Wow,” he said.
And even as he spoke, the glow of the rocks began to fade. It must only be visible for a few minutes after sunset, he thought, when it grows dark enough for the faint luminescence to be visible, but before the sky-glow disappeared completely. Maybe it was only visible in the depth of the canyon.
“Unless you are intending to kill us all,” Estrela said, “I think it is time to stop now.”
18
Falling Stars
They had inflated the bubble in the twilight, but never before in full darkness.
Tana was too restless to be able to go to sleep; too many thoughts were crowding in her head. She had been crammed inside the rockhopper with the others for hours; she needed to be alone for a while. She hesitated outside the airlock to the bubble.
It was against all safety regulations for her to stay outside unless at least one other was outside to be her suit-buddy. “It’s been a long day,” Ryan said. His voice was hoarse and sounded weary. “Come inside. We all need the rest.”
She shook her head, even though she knew that he couldn’t see it inside her helmet. “I’m staying outside,” she said. “Just a little while.”
“Come on, Tana. You know that you’re not supposed to stay outside alone.”
“So try and stop me,” she said, and she looked at Ryan with a look so haggard and forlorn that Ryan couldn’t think of anything to say.
“At least don’t get out of sight of the hobbit bubble,” he said, and she nodded, then turned and walked into the dark.
The dark. It calmed her to just sit in the dark. She could let her mind go blank. She didn’t have to think. She sat on a boulder, her back to the habitat so it didn’t intrude on her consciousness. It was like a moonless night in the desert in West Texas, or anywhere. The stars were clear and bright; she was surprised how bright they were, barely dimmed by the dust. They were the same familiar constellations, but oddly tilted: Orion lying on his sword, Leo with his lion nose pointing to the ground. She couldn’t find the pole star, and then she suddenly realized that she didn’t even know what the pole star for Mars was, or whether it even had one.
A meteor flared overhead, a bright streak of green in the sky, and then darkness again. Then a second meteor crossed the sky, in the same westward direction as the first, and a third followed it, this one bright enough to illuminate the landscape with a taint light. A meteor shower, she thought.
One summer night when she had been six, her grandmother had come into her room and gently shaken her awake. The clock in the kitchen showed two in the morning. They had gone outside, Tana in her pajamas, and her grandmother spread quilts on the grass for them to sit on. Philadelphia spread a ghostly glow on the horizon to the east, and they faced west, toward the darkest part of the sky. “Lie back and watch,” her grandmother had told her. The night air was pleasantly cool against her pajamaed skin, but she wasn’t at all sleepy. She had always been able to wake up at any time and stay awake. In the speckled darkness above her, she saw a flash of light streak across the sky. And another, and then a pack of three traveling together, and then one that streaked across the sky and exploded in a burst of color.
“It’s beautiful,” she said. “What are they?”
“Folks call them falling stars,” her grandmother told her. “They visit us round about this time every year.”
“But what are they?” she insisted.
Her grandmother was silent for a moment. “When I was a little girl,” she said softly, “my grandmother told me that it’s the souls of dead folks, rising up to heaven. When they rise, you see, they go and shed all the sin they’ve been carrying with them, ’cause where they’re going, they don’t need to carry sins around with them no more.” She paused, and another shooting star flashed by, so bright that it lit up the night like fireworks. “Some folks must be carrying around a powerful load of sin, I reckon.”
That was long ago. With her rational mind, Tana knew that it was a meteor shower; tiny bits of ice and sand whizzing through space, burning up in the tenuous outer reaches of the atmosphere. But somewhere deep inside, she thought, John Radkowski is making his last flight, and he’s leaving behind everything he doesn’t need, peeling it away like a soggy overcoat. I wonder what he was carrying round with him, that makes so much of a show when it burns up.
Goodbye, John. Goodbye.
19
Meteors
Ryan Martin had inspected the dome and was hesitating outside when a sudden flash of light attracted his attention. Wow, that was an impressive one, he thought. Looks like it almost hit us. And then there was another, and then a third.
It’s a meteor shower, he thought. No, more than just a shower—this was rally a meteor storm. Streaks of light, yellow, blue. One streaked by and seemed barely over his head, as if it were close enough to touch. Jesus, he thought. Could that one really have been as close as it looked?
Are we in danger? Are we going to get hit?
For a moment Ryan was frightened, and then his rational mind whispered, you know better than that. On Earth, meteors burn up in the tenuous fringes of the atmosphere, a hundred kilometers up. A very few of the largest ones may penetrate as low as forty kilometers before being slowed and shattered by the atmosphere. The atmosphere of Mars was thin, but it was not that thin—the meteor shower might look close, but it was still no more than grains of dust burning up tens of kilometers above their heads, a light show of no practical danger to anyone on the surface.
Meteor showers on Mars have different dates, he thought, different radiants from those on Earth. Who knows the dates of Mars meteor showers? This one probably happens every Mars year at this time, and since Mars is closer to the asteroid belt than Earth, the show is correspondingly more impressive.
He watched it for a few more minutes—on Earth he’d always loved meteor showers; he marked them on his calendar so he wouldn’t forget to watch—and then went into the habitat.
20
On the Ridge
In the morning the first task was to unpack the dirt-rover from its carrying harness on the rockhopper.
Trevor, as usual, was the first one awake. He stepped outside the dome. He stopped, astounded. The yellow-red of Mars had vanished. The adobe-yellow sky had vanished, and had been replaced with a dome of opalescent white. Not one, but three suns were rising into the sky, and around the central sun was an enormous half-circle of light, a red-rimmed halo that just met the twin suns to either side. Even as he watched, the two second suns stretched out into arcs, and a third luminous arc formed above the sun.
At last Trevor found his voice. “What is it,” he said. “What is it?”
Ryan stood beside him. Trevor hadn’t noticed him leave the dome. He was silent for a moment, taking in the sight, and then said, “Parhalia.”
“What?”